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Ensures flux bits are observable for two cycles rather than one; it should be 1us.

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This commit is contained in:
Thomas Harte 2018-07-31 23:01:11 -04:00
parent c91eaaf8da
commit 98bb5bd9f1
2 changed files with 8 additions and 1 deletions
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8
Components/DiskII/DiskII.cpp
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@ -73,13 +73,18 @@ void DiskII::select_drive(int drive) {
drives_[active_drive_].set_motor_on(motor_is_enabled_);
}
// The read pulse is controlled by a special IC that outputs a 1us pulse for every field reversal on the disk.
void DiskII::run_for(const Cycles cycles) {
if(preferred_clocking() == ClockingHint::Preference::None) return;
int integer_cycles = cycles.as_int();
while(integer_cycles--) {
const int address = (state_ & 0xf0) | inputs_ | ((shift_register_&0x80) >> 6);
inputs_ |= input_flux;
if(flux_duration_) {
--flux_duration_;
if(!flux_duration_) inputs_ |= input_flux;
}
state_ = state_machine_[static_cast<std::size_t>(address)];
switch(state_ & 0xf) {
default: shift_register_ = 0; break; // clear
@ -200,6 +205,7 @@ void DiskII::set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk, int driv
void DiskII::process_event(const Storage::Disk::Track::Event &event) {
if(event.type == Storage::Disk::Track::Event::FluxTransition) {
inputs_ &= ~input_flux;
flux_duration_ = 2; // Upon detection of a flux transition, the flux flag should stay set for 1us. Emulate that as two cycles.
decide_clocking_preference();
}
}

1
Components/DiskII/DiskII.hpp
View File

@ -121,6 +121,7 @@ class DiskII:
ClockingHint::Preference clocking_preference_ = ClockingHint::Preference::RealTime;
uint8_t data_input_ = 0;
int flux_duration_ = 0;
};
}